The only notable coming-together: the stormy merger of Sterling, Cooper, Draper and Pryce with former rival ad agency Cutler, Gleason and Chaough, which has assembled a bickering band of ad execs only slightly more collegial than either house of Congress.

Is the unmoored zeitgeist of 1968 to blame for this season’s pattern of upheavals? Does the Vietnam War, the assassinations and riots help account for the turmoil on the show? Or the ’60s drug culture (they smoke pot at the office, and on one episode, a Dr. Feelgood arrives with a hypodermic needle to keep everybody energized)?

Whatever, the psyches on “Mad Men” in this, its sixth and penultimate season, seem to be unraveling as the season finale approaches (Sunday at 10 p.m. EDT on AMC). The male psyches, anyway.

On the other hand, the sisters increasingly are doin’ it for themselves.

Peggy Olson is stronger, more clear-eyed and outspoken than ever. (In last week’s episode, she read Don the riot act: “You’re a monster!”)

Tough, pneumatic Joan Harris, who since the series began has fashioned an unlikely rise from office manager to agency partner, has truly come into her own in recent weeks, notably when she went rogue and landed a major account all by herself (a no-no for a woman in this Alpha Male shop).

Don’s ex, the remarried Betty Francis, seemed to step outside her pouty state of victimhood in a recent episode to forcefully remind Don that he still has feelings for her.

But who knows what awaits Megan, Don’s devoted wife? In love with Don but unsettled by his growing detachment (even as she remains oblivious to his cheating), she seems poised to become the latest Draper roadkill.

“That poor girl,” said been-there Betty to Don. “She doesn’t know that loving you is the worst way to get to you.”

All in all, it’s been a satisfying, illuminating season well served by the superb cast, including Jon Hamm, Elisabeth Moss, John Slattery, Vincent Kartheiser, Christina Hendricks and Jessica Pare.

In his new supporting role, Harry Hamlin as a courtly, quirky agency partner has been a delight in his every scene. Likewise, eager-beaver enigma Bob Benson (James Wolk) has been fun to watch while raising questions from the audience (Just what’s his game at the agency?) and inspiring wild speculation (a government spy?!).

And Linda Cardellini has been a revelation as Sylvia, the latest woman Don believed he had to have, and did, with a calamitous outcome.

“Mad Men,” which arguably has never really been about advertising, seems this season to have taken a step further back from the nuts-and-bolts of Madison Avenue. At the office, the internecine bickering, politics and posturing seem to leave little time for creating ads. Even conference-room sparring about butter versus margarine seemed more about one-upmanship than selling a product.

This season, as usual, “Mad Men” stuck to its elliptical ways, rarely saying too much or gobsmacking the viewer with an OMG moment.

All the more shocking, then, when in a recent episode – by the worst mischance – Don’s teenage daughter, Sally, caught Don in the sack with Sylvia.

For a girl already alienated by her parents’ divorce, by her own roiling adolescence and perhaps – who knows? – by the youth rebellion the ’60s are fomenting, this sight is clearly traumatic (and perhaps all the more so, since Sally was nursing a crush on the Rosens’ teenage son). It’s a lot to bear for this member of the youth generation already conditioned not to trust anybody over 30.

And Don knows it. Throughout the season, he seems to have hastened a downward slide. Not only has his private life been extra messy, he has also sabotaged his agency’s campaigns and messed up a stock offering that stood to make him and his partners rich.

Now, after Sally barged in on him, his shame is beyond measure. At last week’s fade-out, viewers left him in a state of surrender: on his office couch, curled in a fetal position.

Among the questions for the season finale: How can Don begin the process of redeeming himself? And will he?